End-to-end capacity and priority management through multiple packet network segments

ABSTRACT

Apparatus and method for management of a communications network are provided. An exemplary method includes receiving at a first network a notice of an intended communication to a called party network, wherein the intended communication requires at least one resource for supporting a streaming data protocol between a calling party network and the called party network; verifying resource availability of at least one resource in the first network; and in parallel with said verifying, forwarding the notice of an intended communication to a second network and toward the called party network prior to receiving an indication of resource availability of the at least one resource in the first network required for the intended communication.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application,“Method And Apparatus For End-To-End Capacity And Priority ManagementThrough Multiple Packet Network Segments”, 61/188,364 filed Aug. 8, 2008concurrently herewith. The entire teachings of the above application areincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to the field of communication systems, and, morespecifically, to a resource control and policy-based managementmechanisms adapted to implement services including priority services.

BACKGROUND INFORMATION

Often, a call may go through several service provider networks in orderto connect from a calling party to a called party. Each serviceprovider's network may include several domains (or administrativeboundaries). In Time Division Multiplexed (TDM) Networks, resourceclearance using signaling messages is supported through serial resourceclearance on a link-by-link basis. In the serial (or sequential) case,no node transmits a message until first obtaining resource clearancewithin its domain. Accordingly, the total time required to set up a callor session with a link-by-link signaling method is O (τt_(i)) wheret_(i) represents the time it takes for resource clearance in the i-thlink.

Priority services is the name given to preferred treatment of certainkinds of traffic (e.g., media/data and signaling) over other kinds oftraffic in, for example, the context of civilian or defensecommunication networks. Priority in a public switched telephone network(PSTN) is performed on a switch by switch basis. Calls for priorityusers, such as government entities pass through switches whilenon-priority traffic is blocked.

Three kinds of priority services exist as present; namely, wirelesspriority service (WPS), Government emergency telecommunications services(GETS) by national communications systems (NCS) and multi-levelprecedents preemption (MLPP) by the United States Department of Defense.

GETS provides an ability to preempt calls at a lower priority than MLPP.GETS also provides for buffer-type queuing of a call such that the callwill be the first call to pass when a necessary resource becomesavailable. Call control functionality includes the decision of choosingwhich call to allow and which call to preempt. Resource control andpolicy-based management functionality includes the decision of when topreempt a call or when to buffer-type queue a call.

Within the context of voice, video and other data communications (e.g.,multimedia communications and the like) via packet based networks (e.g.,Ethernet, etc.) resource clearance is handled on a sequential basis.Methods for preemption and priority handling of voice calls andmultimedia services are also lacking in packet based networks.

SUMMARY OF THE INFORMATION

A network element, apparatus and method for combining call admissioncontrol and priority services within different type of networks isprovided. A logical functional entity denoted as a Priority ServicesFunctional Element (PSFE) enables administration of priority servicesand call or session admission control policies through interactions withCall Session Control Function Element (CSCF) and Resource Access ControlFacilities (RACF). Method steps in exemplary embodiments may includeverifying the priority levels, receiving resource availabilityinformation, storing call admission and resource allocation information,identifying path and link information required for an originatedsession, checking available resources at links against requiredresources for the call or session establishment, and communicatingresource availability indication/s (or lack thereof) based on admissioncontrol policies after resource verification.

The PSFE allows for capacity and priority management in parallel overall the links in the bearer path within a particular network. PSFEs indifferent networks can also communicate to enable PSFEs in each networkin the path to perform resource clearance independently and in parallel(i.e., undertaking apparent or actual performance of more than oneoperation at a same time). Proposed methods allow both kinds ofparallelization in networks of different architectures, such as IMS andSIP, and also across varied networks. The PSFE introduces obtainingparallel resource clearance across network boundaries, includingheterogeneous networks. In this manner, calls or sessions may beestablished efficiently, and varied features provided in a multi-medianetwork.

PSFE may use Session Initiation Protocol (SIP) messages to communicatewith Signaling and Service Layer entities, such as Proxy (P-) orInterrogating (I-) CSCFs, Subscriber Information Databases (e.g., HomeSubscriber Server or HSS), and Application Servers (AS). PSFE may alsocommunicate with Transport Layer entities (such as, RACF in an all IMPMultimedia Subsystems (IMS) architecture) using, for example, Diametermessages. However, PSFE may integrate both IMS and non-IMS NextGeneration Service Provider (NGSP) networks and enable efficientresource verification and allocation in the non-IMS NGSP also. Further,the PSFE may also determine resource availability using open loopcontrol or other accounting methods in a network without a RACF.

Parallel resource clearance is useful in establishing variousmulti-media services in all IP-based networks regardless of the types ofusers and may be utilized in Enterprise, Commercial Service Provider,Civilian Government, and Military network segments of IP networks. Incontext of priority services, such a PSFE can provide higher priority topriority service users and queue such users' requests for resourceavailability ahead of resource needs from other, routine users. Prioritysession requests and associated priority levels can be identified by thePSFE, for example, through Resource Priority Headers (RPH) in the SIPmessage. It is important to note that to queue priority sessions aheadof routine sessions, no routine session can be allowed in any of thelinks in the priority session path. Coordination of such activitiesacross multiple network segments, which is quite complex among CSCFs,Back to Back user Agents (B2BUAs), and Session Border Controllers (SBCs)in separate network segments, can be achieved via communicating PSFEsdeployed in these segments.

Apparatus and method are provided for capacity and priority managementof a communications network for use in a system having a plurality ofnetworks. An exemplary method includes receiving at a first network anotice of an intended communication to a called party network, whereinthe intended communication requires at least one resource of the firstnetwork for supporting a streaming data protocol between a calling partynetwork and the called party network. In parallel, resource availabilityof at least one resource in the first network is verified and the noticeof an intended communication is forwarded to a second network and towardthe called party network prior to receiving an indication of resourceavailability of the at least one resource in the first network requiredfor the intended communication. For example, resource availability ofresources necessary for the intended communication are not queried andreserved sequentially from calling to called party but query andreservation of necessary resources occurs simultaneously or nearsimultaneously.

The indication of resource availability may include an indicator ofresource sufficiency associated with the intended communication.Verifying resource availability of at least one resource in the firstnetwork may include reserving the resource if the resource is available.In further embodiments, the indication of resource availability of apredetermined resource required at the second network for the intendedcommunication is received at the first network and a re-invite for theintended communication may be forwarded to the second network and towardthe called party network in the event the indication of resourceavailability indicates resource availability for resources in eachnetwork from the calling party network to the called party network.

In another embodiment, if transit network is interposed the firstnetwork and the second network, a request is forwarded to the transitnetwork for verifying with the transit network a predetermined ServiceLevel Agreement (SLA) and that the SLA assures at least one requirementof the intended communication; resource availability information for thetransit network is received; and a re-invite of the intendedcommunication forwarded to the second network and toward the calledparty network in the event the first indication, the second indicationand the resource availability information for the transit networksignify resource availability for at least one resource in each networkfrom the calling party network to the called party network. Since thecalling party forwards a ringing message in response to a re-invite, inthe event of receipt of a ringing message, a lock message may beforwarded. The lock message instructs use of the at least one resourceverified in the first network for the intended communication.

In one embodiment, the method includes receiving at a first network anotice of intended communication from a calling party network to acalled party network; determining resource availability information forthe first network in response to said receiving; and reserving aresource within the first network in the event of resource availabilitybased on the resource availability information for the first network. Inparallel with the determining step and in response to said receiving,the notice is forwarded toward the called party network prior tocompletion of said determining resource availability information for thefirst network. Further, resource availability information is receivedfor at least one other network associated with the intendedcommunication in the event of resource availability for the othernetwork/s associated with the intended communication and a resourceavailability message forwarded based on the resource availabilityinformation for the first network and the resource availabilityinformation for the other network/s indicating resource availability forthe intended communication.

In embodiments, the resource availability message may be forwardedwithin the first network, fed-forward to the second network andfed-backward toward the calling party network. In one embodiment,resource availability is verified via at least one of an open loopcontrol and an accounting based control. In another, the networkincludes a resource access control function (RACF) through whichresource availability information is obtained. A transit network thatprovides bulk transport services and does not specifically support anyindividual call or session related characteristics may be interposed thefirst network and the second network for supporting a streaming protocoltherebetween. In that embodiment, resource availability is verified forthe intended communication via consult with a Service Level Agreement(SLA) with the transit network in relation to at least one requirementof the intended communication.

Based on the resource availability message, the network may forward aSDPReoffer message or a re-invitation message. In response to receivinga ringing message, reserved resources may be locked. In embodiments inwhich the notice of intended communication includes a priorityindicator, verification of resource availability for a second intendedcommunication having a priority indicator less than or equal to apriority indicator for a first intended communication may be preventedwhile verifying resource availability for the first intendedcommunication.

One exemplary apparatus includes a session control functional element(CSCF) and a priority service functional element (PSFE). The CSCF isadapted to receive a notice of an intended communication from a callingparty network to a called party network, request resource availabilityinformation for the first network in response to the notice, andpropagate the notice of intended communication toward the called partynetwork prior to receiving corresponding resource availabilityinformation for the intended communication. The PSFE is adapted toverify for the intended communication the resource availabilityinformation for the first network in response to a request, receiveresource availability information for at least one other networksupporting the intended communication, forward corresponding resourceavailability information to the CSCF, and store resource allocationinformation. The PSFE reserves a resource within the first network inresponse to verifying resource availability for the first network. ThePSFE also forwards the corresponding resource availability informationto the CSCF in the event the resource availability information for thefirst network and the resource availability information for the at leastone other network indicate the intended communication has resourceavailability.

In one embodiment, the CSCF transmits a re-invite message for theintended communication in the event the corresponding resourceavailability information indicates resource availability for eachnetwork from the calling party network to the called party network.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts a network topology for facilitating calls through variousnetworks according to an embodiment of the invention;

FIG. 2 depicts an overview of a network topology for facilitating callsthrough an exemplary network according to an embodiment of theinvention; and

FIG. 3 depicts a flow diagram of an exemplary routine according toembodiments in accord with the invention.

To facilitate understanding, identical reference numerals have beenuser, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

The subject invention will be primarily described within the context ofvoice calls. However, since the subject invention is directed to thebroader issues of multimedia services (including voice calls) referencesto calls and communications within this specification should be broadlyconstrued to include voice, video, audio, email and other multimediacommunications.

Specific structural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments. Exampleembodiments may, however, be embodied in many alternate forms and shouldnot be construed as limited to only the embodiments set forth herein.

The subject invention enables the establishment and management of VoIPtraffic, including traffic of different priority levels, in a network(for example an Internet Protocol (IP) network) with parallel resourceclearance and monitoring of criteria indicative of importance of a newvoice call entering the network, network capability and instantaneousload. Accordingly, an exemplary telecommunications system is describedas one potential environment in which a subject invention operates andexists.

Generally speaking, the invention assists in enabling the followingsystem and network characteristics: (1) A profitable uniformarchitecture that addresses the requirements for both DoD and NCS; (2) Aminimization in the overlap functionality in terms of development andmaintenance of priority service features; (3) A minimization of theimpact on existing architectures; (4) Addressing the requirements of IMSas well as non-IMS environments; (5) An ability to add on priorityservice at any time by a network provider; (6) An interoperability withnetwork solutions of multiple vendors; (7) An ability to pass prioritycalls earlier than routine calls, when a congestion has been cleared andability to maintain “current gets/wps voice functionality” which mayrequire an ability to mimic priority signal queuing from a TDMenvironments; (8) An adaptation to IMS and non-IMS based Next Generationnetworks; (9) An ability to extend and support, at leastarchitecturally, multimedia applications and mid-call features forpriority services in the future; and (10) the providing of calladmission control.

The present invention provides for a logical functional entity denotedas a priority services functional element (PSFE) that integrates withboth IMS and non-IMS networks and environments. Within the context ofnetwork architectures adapted to utilize a PSFE, the PSFE is added tothe architecture as an additional logical entity, such that the rest ofthe network architecture remains substantially unmodified. The PSFEinteracts with the session initiation protocol (SIP) proxies, callsession control functions (PCSCF), resource access control facilities(RACF), (NGSP) and other PSFE entities.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these term since such terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments. Asused herein, the term “and” is utilized in the conjunctive anddisjunctive senses and includes any and all combinations of one or moreof the associated listed items, and the singular forms “a”, “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. Unless otherwise defined, all terms(including technical and scientific terms) used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich example embodiments belongs. It will be further understood thatterms, such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

It is noted that the PSFE can also perform its intended function withoutthe use of a RACF. In that instance, control of specific links isachieved via accounting based methods (whereas control of an entirenetwork is performed with a RACF). In one embodiment, a standard orcommercial network architecture is modified to use a PSFE by providersseeking NCS compliance, though mandatory use of PSFE is envisioned forDoD networks. Optionally, PSFE interaction with H323 systems isprovided. The invention may be utilized within the context of SIP, H323,voice over IP (VoIP) or, more generally, X over IP network (XoIP), whereX is a voice, video or multimedia communication.

The PSFE may provide priority signal message queuing (queuing tracked bylinks of a transport path) and preemption capabilities (i.e., it is ableto identify the calls that need to be preempted to decongest certainlinks). Queuing in this context refers to the buffering-type queuing asis known in the prior art. Queuing in the inventive context is termed bythe inventor as protocol level queuing and includes buffering-typequeuing as well as call state queuing. Queuing a call or other serviceoccurs when, for example, resource availability is verified for a linkduring parallel resource clearance. In this case the call is notdropped; rather, its state is stored by the PSFE until appropriateresources become available for the call in each network to be traversedby the call. Being held or stored means that the state information ofthe call is stored for subsequent use. The state of a call comprises thecall source, the call destination, the resources needed to support thecall, and so on.

Call admission control in a simple form is defined as determining whichcalls should be dropped and which calls should be allowed. Priorityservices in a simple form is defined as providing preferential treatmentto some calls and not other calls. To effectively perform call admissioncontrol and priority services, the network needs to have knowledge ofthe calls in the system, their actual call paths (control plane andmedia plane paths) as well as the transport resources available in thenetwork. One embodiment of the invention includes within one entity (thePSFE), priority and call information (e.g., number of calls in system,available transport resources and the like) needed to combine andcontrol call admission and priority service functions. Thus, the PSFEhelps to simplify network control plane architecture by combiningmultiple priority-related functions (e.g., call admission control andpriority services) in a single functional entity.

The PSFE optionally communicates via Diameter to a RACF. The PSFE mayalso be call-state aware such that it can identify calls over links in atransport network (transport resource aware). In some embodiments, thePSFE continuously polls a RACF to identify availability of resource suchthat resource clearance of multiple call paths may be handledefficiently. In some embodiments the PSFE operates without a RACF (E.g.,for open loop or accounting based controls).

In some embodiments, additional support for the PSFE is beneficial.Specifically, at times it may be appropriate for a RACF to pass linkinformation of a media path (e.g., via a PDFE) to the PSFE. However,this will be needed only under certain cases. RACF link information isnot needed when a call flows or when a priority call is cleared. For apriority call not cleared by the RACF, link information is needed forall subsequent RACF-cleared calls so that the availability of resourcessupporting the non-cleared priority calls can be determined.

Optionally, a P-CSCF (or a Proxy in non-IMS cases) will pass every SIPmessage it receives to the PSFE. Optionally, a new 5xxx message toconvey network attempts (e.g., in the case of priority call queuing) isappropriate. Optionally, a protocol between the PSFE and NGSPs may beadapted to address fault tolerance issues such that fault tolerancefunctionality need not be distributed across a number of CSCFs.

FIG. 1 depicts a network topology facilitating calls through variousnetworks according to an embodiment of the invention. Specifically, FIG.1 depicts an exemplary communications system 100 according to anembodiment of the invention. In addition to architecture, FIG. 1 alsodepicts control and bearer signal paths, which signal paths areassociated with reference numerals indicative of a temporal order ofutilization in establishing and tearing down calls. FIG. 1 will bediscussed in conjunction with other FIGs. to illustrate various callflow examples according to embodiments of the present invention.

Specifically, FIG. 1 depicts a plurality of networks including a callingparty home network 110, a called party home network 120, a calling partyvisited network 130 and a called party visited network 140.

The calling party home network 110 comprises one or more applicationservers (AS) modules 112, a home subscriber server (HSS) 114 and aserving call session control function (S-CSCF) 116.

The called party home network 120 comprises one or more applicationservers (AS) 212, a home subscriber server (HSS) 214, a serving callsession control function (S-CSCF) 116 and interrogating call sessioncontrol function (I-CSCF) 128.

The calling party visited network 130 comprises a P-CSCF 131, a priorityservices functional element (PSFE) 132, a resource allocation controlfunction (RACF) 133, a backbone packet network 136 and an access network137. The RACF 133 includes a policy decision functional element (PD-FE)134 and a traffic resource control functional element (TRC-FE) 135.

The called party visited network 140 comprises a P-CSCF 141, a priorityservices functional element (PSFE) 142, a resource allocation controlfunction (RACF) 143, a backbone packet network 146 and an access network147. The RACF 143 includes a policy decision functional element (PD-FE)144 and a traffic resource control functional element (TRC-FE) 145.

The network 100 FIG. 1 may be modified to represent a conventionalnetwork by removing each PSFE and RACF from the calling and called partyvisited networks. In this case, a call between A and B is initiated inaccordance with the numbered signal paths 1-16; namely (1) a callinvitation is communicated from endpoint A via access network 137 tobackbone packet networks 136, then (2) to P-CSCF 131 and then to (3)S-CSCF, which (4) queries HSS 114, (5) AS 112 and (6) DNS 150 toretrieve the appropriate information pertaining to the called party andits home network. S-CSCF 116 then (7) communicates with the I-CSCF 128of the called party home network. I-CSCF 128 propagates the request (8)to S-CSCF 126, which communicates (9) with its local HSS 124 and (10) AS122 together necessary information regarding endpoint B. S-CSCF then(11) propagates a message to the P-CSCF 141 of the called party visitednetwork 140 associated with endpoint B.

The above steps (1-11) are fairly conventional. In a conventionalnetwork, the P-CSCF 141 communities with a backbone packet network 146to identify those router and other output ports within the RTP streamcapable of supporting the call. This information is propagated back tothe P-CSCF 131. The P-CSCF 131 and P-CSCF 141 cause their respectivebackbone packet networks 136 and 137 provide a communication pathsupporting the call within the RTP stream.

The network 100 of FIG. 1 is depicted as including a PSFE and RACFwithin each of the calling and called party visited networks. Theinteraction of these components with each other and existinginfrastructure will be described in more detail below with respect tothe remaining figures.

Within the context of the present invention, a SIP Proxy (or P-CSCF)continues to work as a transaction-stateful or call-stateless proxy asregards all other features. All calls, independent of priority, to orfrom a SIP Proxy (or P-CSCF) are locally looped to a PSFE. The PSFEoptionally maintains call-state information (including linkidentification information for the traversed links associated with thecall) for all calls. Communications between PSFE and RACF are viadiameter for necessary resource clearance, and various demands andrequests necessary transport path information.

Advantageously, the PSFE enables parallel resource clearance acrossnetwork boundaries, queuing a call in itself until resources becomeavailable. In order to set up calls in parallel across multiple links,the following call control functions are provided: i) call-stateawareness about existing and in-progress calls/sessions; ii) ability togather information regarding resource usages at the links and networkelements, and iii) ability to correlate call path within its domain fromthe addresses. In one embodiment, the PSFE obtains all necessaryresource clearance for a particular call in one parallel operation. ThePSFE performs necessary signal message queuing when it decides thatresources are available with its domain for a call as part of resourceverification. The PSFE routinely polls the RACF to identify resourceavailability. The PSFE sends back appropriate (e.g., standard SIP) errormessages to the SIP Proxy (or CSCF) to signal a call that is to beblocked, if need be (e.g., a higher priority call is queued). In theevent of resource availability for the PSFE's own network and receipt ofan indication of resource availability for another network to betraversed by an intended call, the PSFE sends back appropriate(standard) SIP protocol messages to the SIP Proxy (or CSCF) to signal acall that is to be allowed. The PSFE initiates 3rd party calling forqueued calls via the P-CSCF, as and when the resources for those callsbecome available. In the case of a 3^(rd) party call, the networkoperates to communicate (i.e., call back) both the calling party and thecalled party at a later time.

While denoted as a realtime transport protocol (RTP) stream in FIG. 1,the backbone packet networks may communicate via any streaming protocol,such as transmission control protocol (TCP), user datagram protocol(UDP) and the like. Signaling messages are sent from the call controlelements in the originating network up to the call control elements inthe terminating network for setting up end-to-end voice, data and videosessions across multiple networks. Different mechanisms for carryingsuch messages can be put in place depending on the network topology,interconnectivity, and protocols supported by the underlying network.

FIG. 2 depicts an overview of a network topology for facilitating callsthrough an exemplary network according to an embodiment of theinvention. A method according to the invention proposes to obtainresource clearance in parallel across all links within a networkboundary, as well as obtain resource clearance across several networkboundaries. A conventional system employs sequential resource clearance,in which no node transmits a message until that node first obtainsresource clearance within its domain. (i.e., serial resource clearanceis accomplished on a link-by-link basis). In contrast, in parallelresource clearance as provided by the PSFE, the apparent or actualperformance of more than one resource clearance operation occurs at atime, by the same or different devices and modules. In the parallelcase, the various time requirements for resource clearance (Ti) aretriggered as and when a resource availability request is received indomain i, and the domain i does not wait for the completion of Ti beforesending a resource availability request to domain i+1. In this manner,multiple domains may be obtaining resource clearance without having towait for the completion of resource clearance in a previous one/s. Whenthere are multiple links in each domain, resources clearance within adomain may also be performed in parallel. For example, by using PSFEsfor obtaining resource clearance in parallel across all links within anetwork boundary, as well as obtaining resource clearance across severalnetwork boundaries, the time required for resource clearance will bereduced to O(Max(t_(i))), where Max(t_(i)) represents the maximum of allt_(i), i.e., the maximum of all individual resource clearance times inindividual links. Accordingly, the time required to process and transmita message in a PSFE enabled network is much lower than the time requiredto wait for clearance on all links in a conventional network.

Such a methodology leads to one or more benefits. For example, settingup calls and sessions across an IP network will be more efficient andfaster, which will reduce post-dial delay. Calls and sessions will havehigher probability to complete set-up protocol exchanges before anyparticular timer expires, such as during set up when the networks arecongested. For an end-to-end call which encounters multiple serviceprovider (SP) networks, each SP network may be provided with informationon resource needs and priority for the call/session, and the separatenetworks are able to assess and clear the calls. The time for set up ofa call or a session that crosses several network domain boundaries(resulting from reasons, such as, administrative domains, geographicaldistribution, and population density, etc, even within a same SPnetwork) will require only the maximum time required for setup in any ofthe domains.

Further, beneficial applications can be developed using the methodologyprovided. For example, the resource needs and priority assignment fromthe originating network/user may be communicated globally in a trustedmanner with private mapping of such priority assignments at eachseparate network for specific internal usage within each network asdescribed in U.S. patent application Ser. No. XX/XXXXXX entitled RHPMapping And Defaulting Behavior, filed Dec. XX, 2008, which is hereinincorporated by reference. Many call scenarios require connection tomedia servers, at times prior to call establishment and in other casesin mid-call, and the access path to media server may differ from thatcarrying the bearer packets from the caller to the called. The proposedmethodology enables reservations and resource management across suchdifferent paths in parallel. In addition, the methodology of theinvention facilitates the establishment of multiple conference legs,where call legs for an intended communication may include legs for eachend point (end point referring to users, media server, conferencingserver, and the like) and for each media type (e.g., video, audio, text,data, and the like, and some combination thereof) and some combinationthereof. For example, if capacity is constrained to support all mediatypes in a multi-media call, reservations across media types in parallelcan be utilized to enable early establishment of calls with one mediarequiring lesser capacity when required capacity to support all mediatypes is unavailable at the start of the call. Later, other media typescan be added when additional capacities become available as furtherdescribed in U.S. patent application Ser. No. XX/XXXXXX entitledIncremental Addition And Scale-Back of Resources Adapting to NetworkResource Availability, filed Dec. XX, 2008 which is herein incorporatedby reference. Further conferences with multiple end points acrossvarious network may be initially established with less than all of themultiple end points, with endpoint called back as resource becomeavailable as described in U.S. patent application Ser. No. XX/XXxxxXentitled Network Call Back To Add Conference Participants And/Or Media,filed Dec. XX, 2008, which is herein incorporated by reference.

An overview of the mechanism for the parallel resource clearance by PSFEacross multiple networks is outlined in FIG. 2. For example, a call maybe initiated initiated from a caller in network A to a called end innetwork B and will traverse network 200, which comprises networks A 210,B 220 and C 230. Alternatively stated, a call initiated from a caller toa called end will traverse networks N₁, N₂, N₃, N_(i), . . . N_(M).,where N₁ is the head end, and N_(M) is the tail end of the call. Thehead end refers to network components like proxies, CSCF and PSFEsclosest to the caller, while tail end refers to those network componentsclosest to the called user. Also note that only three networks, namelyA, B and C are illustrated for simplicity.

Each network includes a CSCF (212, 222, 232), a PSFE (212, 224, 234), aRACF (216, 226, 236), and a backbone packet network (218, 228, 238). Thebackbone packet network in each network may include a plurality ofservers (219, 229, 239). The RACF may include a policy decisionfunctional element (PD-FE) and a traffic resource control functionalelement (TRC-FE) (not shown)

All calls, independent of priority, to or from a CSCF are locally loopedto a PSFE. The PSFE maintains call-state information (including linkidentification information for the traversed links associated with thecall) for all calls. Communications between PSFE and RACF are viaDiameter for necessary resource clearance, and various demands andrequests necessary transport path information.

When a call passes through networks A, B and C, then the PSFE element ineach of those network clouds is responsible for obtaining necessaryresource clearances in its own network respectively. In parallel withthe verification of resource availability within its network, the PSFEforwards the notice of an intended communication to the next network andtoward the called party network. As resources become available in eachof the networks, the PSFEs in that network await for the clearance toarrive from the tail end of the call. In other words, network B waitsfor the clearance from network C, and network A waits for the clearancefrom network B. Thus, network A will not receive clearance until bothnetworks C and B have necessary resources for the call. At this pointthe PSFE in network A, communicates to the CSCF in network A (or the SIPproxy in network A) and triggers a re-invite from the caller to thecalled user. In an alternative embodiment, PSFEs in each of the networksawait for the resource clearance indication to arrive from the head enddirection of the call.

In each of these network segments one or multiple PSFE communicates withthe corresponding CSCF and RACFs. For example, if resource clearance ispropagated toward the tail end, on receiving a new session or callrequest through SIP INVITE and from the identification that the call orsession needs to be forwarded to the CSCF in Network B, the PSFE inNetwork segment A forwards a resource assessment request to PSFE inNetwork segment B, while looking into the resource requirement versusavailability in Network segment A. The PSFE in Network segment A alsofollows up with a message to the CSCF and PSFE in network segment Bregarding resource availability in Network segment A after itsdetermination.

The PSFE in Network segment B performs the same function as the PSFE inNetwork segment A, which is sending a resource assessment request toPSFE in Network segment C by recognizing that the call or session needsto be sent to Network segment C while it gets engaged in verifyingresource availability in Network segment B. PSFE in Network segment Balso follows up with a message to the CSCF and PSFE in Network segment Cregarding resource availability in Network segment B after itsdetermination. PSFE in Network segment B also forwards the resourceavailability determination that it received from PSFE in Network segmentA.

The CSCF in Network segment C determines that the called end is inNetwork segment C. PSFE in Network segment C determines the resourceavailability for the requested call or session for the Network segment Cand together with messages received from PSFEs in Network segments A andB, determines the end-to-end resource availability before informing itsdecision on call or session admission to the CSCF in Network segment C.CSCF in Network segment C then admits or disallows the call based onPSFEs' decision (based on resource availability information for PSFEs inA, B and C).

In other embodiments, a transit network may be interposed two of theNetwork Segments illustrated (e.g., between Network segments A and B,Network segments B and C). A transit network is used for bulk transportbetween networks providing user services. Such transit networks providebulk transport services only and do not have call or session managersassociated therewith but may honor Service Level Agreements (SLA), whichare primarily based on statistically averaged call or sessionperformance over time. SLAs are generally based on connectivity metricssuch as, downtime, reliability and availability measures, and bytessent/received, and Quality of Service metrics such as, delay, delayvariation, packet loss and packet throughput.

Transit networks do not provide individual call or session control andmanagement. Thus, the transit network and its partners will typicallyhave an overall bulk transport carrying agreement but the transitnetworks do not support specifically any individual call or sessionrelated characteristics. For example, a transit network may be outfittedwith a PSFE, RACF and a Backbone network but not have a CSCF.

For calls passing through such core transport networks or transitnetworks, obviously call or session management is not performed by thecore transport service provider. Thus, the originating and/orterminating network service provider on either side of the transitnetwork is responsible to provide end-to-end call or session admission,and management. Accordingly, the PSFE also is enabled to negotiate anddetermine resource availability from the transport-only networks. Inaddition, as described above, the PSFE performs resource assessment inits own network and forwards a resource assessment and clearance requestthrough SDP offers to PSFEs in the call path as determined from thedestination URI. Based on received the availability information for itsown network and other networks in the call path including any interposedtransit networks, a PSFE decides on call admission and instructs theCall Session Control Function Elements (CSCF) for implementing call orsession admission decisions.

FIG. 3 depicts a flow diagram of an exemplary routine according toembodiments in accord with the present invention. The call blocking callflow, call queuing and call creation for the parallel resource clearanceof 300 of FIG. 3 will be described within the context of thecommunications system 200 of FIG. 2. Specifically, control signal pathsbetween calling endpoint-A 302 in network A (i.e., calling partynetwork) and called endpoint-C of network C (i.e., called party network)as can be gathered from FIG. 2 comprise, in the order named, CSCF-A 212,PSFE-A 214, CSCF-B 222, PSFE-B 224, CSCF-C 232, PSFE-C 234.

Referring now to FIG. 3, at 301 an invite message is propagated fromcalling endpoint A to CSCF-A 212, then at 302 to CSCF-B 222, and finallyat 203 to CSCF-C 232. In general, each network sends an invite messagetoward the called network until the called network is reached by thenotice of intended communication.

In parallel with the propagation of the invite message, each PSFE (214,224, 234) verifies resource availability for a resource required forintended communication in response to a reserve message (311, 312, 313).When an invite message enters a first network (e.g., network C), thecorresponding PSFE (e.g., PSFE-C 234) attempts to reserve necessarybandwidth for the call and queues the call in its stack. Thecorresponding PSFE (e.g., PSFE-C 234) determines from corresponding RACF(e.g., RACF-C 236) if resources are available for all the links withinthe first network (e.g., network C) for this particular call. In oneembodiment, if requested resources are not available, the call isqueued, and no lower or equal priority call is allowed until thisparticular call gets a chance to obtain the requested resource capacity.

For example, in case of dynamic real-time bandwidth management,corresponding RACF (e.g., RACF-C 236) listens to the SNMP messages frommultiple switch/routers in that network in parallel and determines ifall the necessary link/s that constitute the call have enough resource/savailable. In cases where dynamic bandwidth management is not requiredand mere call counting or bandwidth counting will suffice, thecorresponding PSFE or the corresponding RACH may be directly involved inbandwidth or call counting and determine the availability of thenecessary resource/s.

The act of queuing the call and communication with the correspondingRACH ensures that resources are obtained in parallel in first network(e.g., network C). In case of dynamic bandwidth management, allcorresponding routers in the network send updates in parallel to thecorresponding RACH of the first network. The corresponding PSFE thenmakes decisions based on the query to the corresponding RACH of thenetwork as described above.

In another embodiment when a transport network is interposed networks Aand B, the originating network's (A) PSFE learns about the network wherethe call/session needs to be forwarded to (i.e., network B) and theintermediate transport network (A′) from the called URI. The PSFE thenverifies the SLA agreed with the transport network (A′) and determinesif the SLA assures the requirements for the call/session in progress.The originating network's PSFE forwards the call/session request alongwith resource needs to the PSFE in the next network (B) in thecall/session path (via the CSCFs).

A PSFE sends a Held message toward the next PSFE closest the head-endPSFE only when the resources in all subsequent networks are availablefor the intended call. If the PSFE is in the called party network (e.g.,network C), at 321 the held message may be forwarded based on resourceavailability within the called network alone. The held message isforwarded between PSFE via corresponding CSCF at 322, 323. For PSFE in afirst network other than called party network (i.e., intermediatenetworks (e.g., network B) and the calling party network (e.g., networkA)), at 321 a Held message is forwarded toward the head-end only if eachnetwork from first network in question to the called party network haveresource availability for the intended communication. Again, the heldmessage is delivered to the head end PSFE via the corresponding CSCF ofthe first network at 325 and the head end network at 326. In otherwords, the held message is forwarded between PSFE via corresponding CSCF(325 and 326). A Held message is essentially a command that instructsthe CSCF that resources are held for a user, but are not yet consumed.The Held message may be implemented as a 1xx message.

As resources become available in each of the networks, the PSFE in thatnetwork await for the clearance to arrive from the tail end of the call.In other words, when a call passes through networks A, B, and C, B waitsfor the clearance from C, and A waits for the clearance from B. Thus Awill not receive clearance until both C and B have necessary resources.All the intermediate networks' PSFEs and the final network PSFE sends a1xx message indicating that resources are held when the resources becomeavailable. Note that, in an embodiment with a transport network A′interposed networks A and B, PSFE in A also has verified that thetransport network A′ can assure the resources required in A′ throughcommunication with the transport network.

In an alternate embodiment, the PSFE sends an indication of resourceclearance to the head-end as soon as resources are determined to beavailable in its own network and the decision about final call admissionmay be based on resources availability across the various PSFE asdetermined by the PSFE at the head end network (i.e., calling partynetwork). In another embodiment call admission may be based on minimumpossible resource is available across the various PSFE.

When PSFE at the calling party network determines that there is ofresource availability for end-to-end communication contemplated, at 327that PSFE triggers corresponding CSCF to initiate a SIP Re-Invite fromthe calling network CSCF to the called network CSCF (328, 329, 330).Alternatively, an SDPReoffer may be triggered.

In respond to the re-invite message, a ringing message is propagatedfrom the called endpoint to the calling endpoint (331, 332, 332). When aPSFE obtains the Re-Invite message, the necessary resource is locked inusing the queued information associated with the call via lock message(335, 336, 337). A Lock message is essentially a command that instructsthe PSFE that resources are now being used. The Lock message may beimplemented as another 1xx message or could be piggybacked with‘ringing’ message. Prior to the PSFE receipt of the Lock message, thecall is merely queued and the resources are not being consumed. Messagesneed not be in SIP, but can be implemented in DIAMETER or any otherprotocol.

The PSFE of the present invention advantageously isolated Parallel CallAdmission and Priority Services development so that such services areeasier to develop and maintain. Moreover, such services may now beprovided without service and software replication with respect to vendorproduct offerings. Parallel Call Admission and Priority Services can bean optional service required by a customer and can fit IMS and non-IMSnetworks, including H323. With the novel PSFE, newer DISA and NGPSfeatures are easier to develop. In this manner, new features like“priority conference call reservation” of priority conferences may beimplemented. In addition, the PSFE relieves the burden of having a CSCFor any other fully operational SIP Proxy maintain resource awareness(i.e., call states with respect to links). The PSFE provides resourcecontrol and policy-based management mechanism adapted to implementpriority services in a packet network environment, such as describedherein.

The above-described embodiments of the invention may be implementedwithin the context of methods, computer readable media and computerprogram processes. Generally speaking, methods according to theinvention may be implemented using computing devices having a processoras well as memory for storing various control programs, other programsand data. The memory may also store an operating system supporting theprograms. The processor cooperates with conventional support circuitrysuch as power supplies, clock circuits, cache memory and the like aswell as circuits that assist in executing the software routines storedin the memory. As such, it is contemplated that some of the stepsdiscussed herein as software processes may be implemented withinhardware, for example as circuitry that cooperates with the processor toperform various steps. Input/output (I/O) circuitry forms an interfacebetween the various functional elements communicating with the device.

A computing device is contemplated as, illustratively, a general purposecomputer that is programmed to perform various control functions inaccordance with the present invention. The invention also can beimplemented in hardware as, for example, an application specificintegrated circuit (ASIC) or field programmable gate array (FPGA). Assuch, the process steps described herein are intended to be broadlyinterpreted as being equivalently performed by software, hardware and acombination thereof in various alternative embodiments.

The invention may also be implemented as a computer program productwherein computer instructions, when processed by a computer, adapt theoperation of the computer such that the methods and/or techniques of thepresent invention are invoked or otherwise provided. Instructions forinvoking the inventive methods may be stored in fixed or removablemedia, transmitted via a data stream in a signal bearing medium such asa broadcast medium, and/or stored within a working memory within acomputing device operating according to the instructions.

While not specifically noted, it will be appreciated by those skilled inthe art that various network management system (NMS) and elementmanagement system (EMS) are used to manage the various functionalelements discussed herein, including the new PSFE. Each PSFE is managedby an appropriate NMS and/or EMS, which is selected according to thenetwork within which the PSFE operates. Thus, the PSFE is operable toprovide bridge and information and protocol bridge between variousmanagement systems such that call state aware and priority state awareinformation may be utilized throughout a large group of networks, asdiscussed above.

Within the context of a NMS or EMS utilizing the present invention, aninstantiation of an application such as an IMS application includes aPSFE that is logically and/or physically disposed between the RACF andCSCF of a network to perform the various functions discussed above. Assuch, one embodiment of the invention comprises a method for adapting acontrol plane of a communication network normally using a call sessioncontrol function (CSCF) in communication with a resource access controlfunction (RACF), where the method includes providing a priority servicefunctional element (PSFE) between each RACF and its corresponding CSCFto verify a priority level for each call, receive resource allocationinformation from the RACF, store a resource allocation for each call,and cause the CSCF to preferentially allocate resources to high prioritycalls as discussed above with respect to the various figures.Instantiations supporting the PSFE may be provided on a single server ormultiple servers, and/or within a single network or multiple networks.

An apparatus according to the invention is adapted for use in a systemcomprising a plurality of networks, each of which include a resourceaccess control function (RACF), a call session control function (CSCF)and a packet network supporting, illustratively, a Realtime TransportProtocol (RTP) stream between the calling and the called party networks.The PSFE advantageously provides a knowledge of call-states as well asthe “links” that they pass through, in order to block routine calls(both NCS and DoD), queue priority calls against the “links” that theywill use (NCS) and tear down/preempt calls, under certain conditions,based on the “links” that they traverse (DoD). The PSFE also provides anability to perform 3^(rd) party calling (network initiated) when queuedcalls are processed, and an ability to obtain “link” (i.e., transportresource paths) information from certain elements in the network. Thisinformation is then passed to the relevant management system.

Reference herein to “one embodiment”, “another embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment can beincluded in at least one embodiment of the invention. The appearances ofthe phrase “in one embodiment” in various places in the specificationare not necessarily all referring to the same embodiment, nor areseparate or alternative embodiments necessarily mutually exclusive ofother embodiments. Although various embodiments which incorporate theteachings of the present invention have been shown and described indetail herein, those skilled in the art can readily devise many othervaried embodiments that still incorporate these teachings.

1. A method comprising: receiving at a first network a notice of anintended communication to a called party network, wherein the intendedcommunication requires at least one resource for supporting a streamingdata protocol between a calling party network and the called partynetwork; verifying resource availability of at least one resource in thefirst network; and in parallel with said verifying, forwarding thenotice of an intended communication to a second network and toward thecalled party network prior to receiving an first indication of resourceavailability of the at least one resource in the first network requiredfor the intended communication.
 2. The method of claim 1 wherein theindication of resource availability includes an indicator of resourcesufficiency associated with the intended communication.
 3. The method ofclaim 1 wherein verifying resource availability of at least one resourcein the first network comprises: reserving the at least one resource inthe first network if the resource is available.
 4. The method of claim 1further comprising: receiving at the first network a second indicationof resource availability of at least one resource at the second networkrequired for the intended communication.
 5. The method of claim 4further comprising: forwarding a re-invite of the intended communicationto the second network and toward the called party network in the eventthe first indication and the second indication signify resourceavailability for at least one resource in each network from the callingparty network to the called party network.
 6. The method of claim 4further comprising: forwarding a request to a transit network interposedthe first network and the second network for verifying with the transitnetwork a predetermined Service Level Agreement (SLA) and that the SLAassures at least one requirement of the intended communication;receiving resource availability information for the transit network; andforwarding a re-invite of the intended communication to the secondnetwork and toward the called party network in the event the firstindication, the second indication and the resource availabilityinformation for the transit network signify resource availability for atleast one resource in each network from the calling party network to thecalled party network.
 7. The method of claim 1 further comprising: inthe event of receipt of a ringing message, forwarding a lock message,the lock message instructing that the at least one resource in the firstnetwork is to be used.
 8. A method of capacity and priority managementfor use in a system comprising a plurality of networks, each of thenetworks including a packet network for supporting a streaming dataprotocol between a calling party network and a called party network, themethod comprising: receiving at a first network a notice of intendedcommunication from a calling party network to a called party network;determining for the intended communication resource availabilityinformation for the first network in response to said receiving;reserving a resource within the first network in the event of resourceavailability based on the resource availability information for thefirst network; in parallel with said determining and in response to saidreceiving, forwarding the notice of intended communication to a secondnetwork and toward the called party network prior to completion of saiddetermining for the intended communication resource availabilityinformation for the first network; receiving resource availabilityinformation for at least one other network associated with the intendedcommunication in the event of resource availability for the at least oneother network associated with the intended communication; forwarding acorresponding resource availability message based on the resourceavailability information for the first network and the resourceavailability information for the at least one other network indicatingresource availability for the intended communication.
 9. The method ofclaim 8 wherein forwarding a corresponding resource availability messagecomprises: forwarding the corresponding resource availability messagewithin the first network.
 10. The method of claim 8 wherein forwarding acorresponding resource availability message comprises: forwarding thecorresponding resource availability message to a third network.
 11. Themethod of claim 8 wherein the second network and the third network arethe same network.
 12. The method of claim 8 wherein determining for theintended communication resource availability information for the firstnetwork is performed via at least one of an open loop control and anaccounting based control.
 13. The method of claim 8 wherein determiningfor the intended communication resource availability information for thefirst network comprises: communicating with a resource access controlfunction (RACF) to verify the resource availability informationconcerning the first network.
 14. The method of claim 8 wherein, whereindetermining for the intended communication resource availabilityinformation for the first network further comprises forwarding a requestto a transit network interposed the first network and the second networkfor verifying with the transit network a predetermined Service LevelAgreement (SLA) and that the SLA assures at least one requirement of theintended communication; and receiving resource availability informationfor the transit network.
 15. The method of claim 8 further comprisingforwarding at least one of a SDPReoffer message or a re-invitationmessage for the intended communication after forwarding a resourceavailability message.
 16. The method of claim 8 further comprisingreceiving a ringing message; and locking the resource within the firstnetwork that was reserved in response to the ringing message.
 17. Themethod of claim 8 wherein the notice of intended communication includesa priority indicator, the method further comprising, while determiningresource availability for a first intended communication, preventingdetermining resource availability for a second intended communicationhaving a priority indicator less than or equal to a priority indicatorfor the first intended communication.
 18. An apparatus for managing afirst network, the first network including a packet network forsupporting a streaming data protocol between a calling party network anda called party network, the apparatus comprising: a call session controlfunctional element (CSCF) for receiving a notice of an intendedcommunication from a calling party network to a called party network,requesting resource availability information for the first network inresponse to the notice, and propagating the notice of intendedcommunication toward the called party network prior to receivingcorresponding resource availability information for the intendedcommunication; and a priority service functional element (PSFE) forverifying for the intended communication the resource availabilityinformation for the first network in response to a request from theCSCF, receiving resource availability information for at least one othernetwork supporting the intended communication, forwarding thecorresponding resource availability information to the CSCF element, andstoring resource allocation information; wherein the PSFE reserves aresource within the first network in response to verifying resourceavailability for the first network and forwards the correspondingresource availability information to the CSCF in the event the resourceavailability information for the first network and the resourceavailability information for the at least one other network indicateresource availability for the intended communication.
 19. The apparatusof claim 18, wherein the PSFE supports at least one of an open loopcontrol and an accounting based control.
 20. The apparatus of claim 18,wherein the first network further includes a resource access controlfunction (RACF), and wherein the PSFE verifies the resource availabilityinformation concerning the first network using the RACF.
 21. Theapparatus of claim 18, wherein the PSFE forwards the correspondingresource availability information to the CSCF in the event the resourceavailability information for the first network and the resourceavailability information for the at least one other network indicateresource availability for each network from the called party network tothe first network.
 22. The apparatus of claim 18, wherein the CSCF totransmits a re-invite message in the event the corresponding resourceavailability information indicates resource availability for eachnetwork from the calling party network to the called party network.